Positioning support information for time of arrival (toa) estimation in possible multipath propagation conditions

ABSTRACT

There is provided a method for providing Observed Time Difference of Arrival (OTDOA) Reference Signal Time Difference (RSTD) measurements from a wireless device to a location server. The method comprises sending, from the wireless node to the location server, a capability to support OTDOA location measurements using multipath RSTD, receiving, at the wireless node, a request for OTDOA location measurements using multipath RSTD, from the location server. The method comprises receiving, at the wireless node, assistance data providing details of required OTDOA location measurements using multipath RSTD from the location server, receiving, at the wireless node, a signal from an RSTD reference cell and a neighbor cell. The method comprises observing, at the wireless node, a time difference between the received signals thereby obtaining the required OTDOA location measurements using multipath RSTD and sending the required OTDOA location measurements using multipath RSTD from the wireless node to the location server.

TECHNICAL FIELD

The present disclosure generally relates to wireless communications,wireless communication networks, and wireless communications nodes anddevices.

BACKGROUND

Location-based services and emergency call positioning drive thedevelopment of positioning in wireless networks, and a plethora ofapplications and services in terminals take advantage of theavailability of the position of the device(s). Positioning in Long-TermEvolution (LTE) is supported by the architecture shown in FIG. 1, withdirect interactions between a User Equipment (UE) 1 and a locationserver 2, namely the Evolved-Serving Mobile Location Centre (E-SMLC) 2,via the LTE Positioning Protocol (LPP). Moreover, there are alsointeractions between the location server 2 and the eNodeB 3 via the LPPaprotocol, to some extent supported by interactions between the eNodeB 3and the UE 1 via the Radio Resource Control (RRC) protocol.

The following positioning techniques are considered in LTE (3GPP36.305):

-   -   Enhanced Cell Identifier (ID), which essentially consists of        cell ID information to associate the UE to the serving area of a        serving cell, and then additional information to determine a        finer granularity position.    -   Assisted Global Navigation Satellite System (GNSS) information,        which is retrieved by the UE, supported by assistance        information provided to the UE from the E-SMLC.    -   Observed Time Difference of Arrival (OTDOA), in which the UE        estimates the time difference of reference signals from        different base stations and sends those to the E-SMLC for        multilateration. Multilateration is a navigation technique based        on the measurement of the difference in distance to two stations        at known locations that broadcast signals at known times.    -   Uplink TDOA (UTDOA), in which the UE is requested to transmit a        specific waveform that is detected by multiple location        measurement units (e.g. Evolved Universal Terrestrial Radio        Access Network NodeBs (eNBs)) at known positions. These        measurements are forwarded to the E-SMLC for multilateration.

In the previously listed positioning methods, it is important toestimate the time-of-arrival (TOA) of a signal at the receiver node,from a sender node. The TOA information can be combined to formmeasurements that support the different fundamental positioning methods:

-   -   the difference between two TOAs from two different sender nodes,        forming a time difference of arrival measurement, e.g. downlink        TDOA;    -   the difference between two TOAs obtained at two different        receiver nodes, based on a signal from a specific sender node,        forming a time difference of arrival measurement, e.g. uplink        TDOA;    -   the difference between the TOA at a node, and the subsequent        transmission time, indicating the processing time of a node, as        well as the difference between a TOA at a node and a previous        transmission time, indicating the total round trip time, forming        components in a ranging procedure.

All TOA based approaches translate measurements into distances andrelative distances based on the signal propagation velocity in theconsidered medium.

In a general scenario illustrated in FIG. 2, a UE A 1 a isserved/controlled by a serving/controlling node 6. In addition, UE A 1 acan detect a signal from one or more non-serving/non-controlling nodes7.

The UE 1 may estimate the TOA of a signal from one node, possiblysubject to an interfering signal from another node within coverage orcommunication range. Alternatively, significant interfering signals fromother nodes may be avoided by employing a muting scheme where nodesalternate transmission and mute according to a schedule. The scenariomay also be reversed, where TOA is estimated in a node, based on asignal from a UE A 1 a, possibly subject to interference from a signalfrom a different UE B 1 b. Moreover, the scenario may also be a UE A 1 aestimating a TOA based on a signal from a different UE, or a nodeestimating TOA based on a signal from a different node.

FIG. 3 illustrates the multilateration in OTDOA while considering eNB1 3a as the reference cell. For example, the Observed Time Difference OfArrival (OTDOA) is a UE-assisted method, in which the UE 1 measures thetime of arrival (TOA) of specific Positioning Reference Signals (PRS)from multiple cells (eNBs 3), and in which the UE 1 computes therelative differences between each cell and a reference cell. TheseReference Signal Time Difference (RSTD) are quantized and reported viaLPP to the E-SMLC 2 together with an accuracy assessment. Based on knownpositions of eNBs 3 and their mutual time synchronization, it ispossible for the E-SMLC 2 to estimate the UE 1 position from the RSTDand covariance reports using multilateration. The accuracy depends onthe radio conditions of the received signals, the number of receivedsignals as well as the deployment, which means that it will varyspatially. One of the factors which significantly impacts on theperformance of OTDOA, is the assumptions on the UE 1 receiver model andhow it estimates the TOA.

Determining TOA

Wireless channels are usually modelled as multipath channels, meaningthat the receiving node receives several distorted and delayed copies ofthe transmitted signal through multiple reflections, diffraction, etc.The multi-path effect can be modelled by considering the followingtapped delay link channel.

${h(t)} = {\sum\limits_{l = 0}^{L}{a_{l}{\delta \left( {t - \tau_{l}} \right)}}}$

where L is the number of multipath taps (i.e., number of signalsreceived at the UE), a_(l) denotes the complex attenuation of the l-thtap (i.e., attenuation of the l-th signal received), τ_(l) indicates thetime delay of the l-th tap and δ(t) is the delta function, which is onewhen t=0 and zero otherwise. In order to determine geographical distancebetween the transmitter and receiver antennas, one should measure τ₀(time delay corresponding to line-of-sight (LOS) tap) and scale it withthe speed of light.

TOA of the signal can be measured based on a reference signal that isknown to the receiver. Let us assume that the transmitted signal isdenoted as “x(t)”, then the received signal “y(t)” subject to multipathchannel is given by

${y(t)} = {{\sum\limits_{l = 0}^{L}{a_{l}{x\left( {t - \tau_{l}} \right)}}} + {w(t)}}$

where w(t) models additive noise and interference. Based on the receivedsignal y(t) and the prior knowledge of the transmitted reference signalx(t), the receiver is interested in computing time delay of the firstchannel tap τ₀ (i.e., TOA of the LOS signal or the signal that arrivesearliest if there is no LOS, since that translates to the distancebetween transmitter and receiver). However, since the received signal isembedded in noise and interference, it is not always easy to determinethe first channel tap if it is not strong enough, which is usually thecase, for example, in the indoor scenarios.

There can be different methods to determine TOA at the receiver. Asimple and widely used method is to cross-correlate the received signalwith the known transmitted reference signal, using

${{R\lbrack\tau\rbrack} = {\sum\limits_{i = 0}^{K}{{y\lbrack i\rbrack}{x^{-}\left\lbrack {i - \tau} \right\rbrack}}}},$

where K is the length of the received signal discrete domainrepresentation. The cross-correlation function R(τ) gives channelimpulse response. The absolute value of R(τ) corresponds to the ProfileDelay Profile (PDP) of the channel. The next step is to determine thefirst channel tap, which can be estimated by determining the first peak{circumflex over (τ)} in R[τ] that is above a certain threshold, using

$\overset{\hat{}}{\tau} = {{\arg \min}{\left\{ {\frac{\left| {R\lbrack\tau\rbrack} \right|}{\max \left\{ {R} \right\}} \geq \zeta} \right\}.}}$

Finding the LOS component based on the cross-correlation as discussedabove, is not an easy task for a UE 1. The UE 1 needs to find a properthreshold in order to find the LOS component since the LOS tap istypically not the strongest tap. If the threshold is too low, thereceiver can falsely detect noise as first channel tap and if thethreshold is too high, the receiver may miss a weak LOS signal.Therefore, there is typically a trade-off between LOS detection androbustness to noise. For example, FIGS. 4a and 4b show situations wherea UE implementing a threshold 11 (the horizontal solid black line in thefigures) based method fails to estimate a proper TOA, indicating theproblems with a threshold based peak detection. In these figures, xcorr8 indicate cross correlation measurements, line 9 indicates exact time,while line 10 indicates estimated time, these times corresponding todistance measurements. FIG. 4a exemplifies a situation where having alower threshold value 11 would have improved the TOA estimationconsiderably. FIG. 4b exemplifies a situation where having a higherthreshold value would have improved the TOA estimation considerably.

To solve this problem, in RAN1#86bis, it has been agreed that multipathRSTD feedback can be reported for up to 2 peaks of each cell.

Additional peaks reporting for downlink positioning

Downlink positioning is based on UE 1 time of arrival (TOA) estimationof positioning reference signals (PRSs) from a reference andneighbouring cells. The UE 1 receiver may detect several occurrences orcorrelation peaks from a specific cell over a time window, and the UEmay try to identify the reference peak as the most likely line of sightpeak. Peaks later in time are considered to be due to non-line of sightpropagation and peaks earlier in time are considered to be due to noise.Additional peaks reporting enables capable UEs 1 to also reportadditional peaks from reference and/or neighbouring cells.

FIG. 5 illustrates a reference and additional peaks in the receivedpositioning reference signals from the reference cell and the neighborcell. This figure shows a possible situation at the UE 1 receiver withboth a reference peak and additional peaks from a reference cell and aneighbour cell. In this example, the UE 1 receiver has detected multipleTOA peaks for both the reference cell and a neighbour cell i. For boththe reference cell and the neighbour cell, the UE 1 estimates referencepeak TOA t₀ and t₁ respectively. The Reference Signal Time Difference isdetermined by the UE 1 as the time difference between these referencepeaks. The reference peak can be selected based on different strategies,such as the peak with the highest likelihood to be a relevant firstpeak, or the first peak among the detected peaks. The selection of thereference peak is implementation specific.

In addition, there are additional peaks illustrated in FIG. 5, which arerepresented by the relative time difference to the reference peak. Forthe reference cell with the reference peak TOA to and TOA of additionalpeaks t_(0,1) and t_(0,2), the additional peaks are represented by therelative time differences δ_(0,1)=t_(0,1)−t₀ and δ_(0,2)=t_(0,2)−t₀.Similarly, for the neighbour cell i with the reference peak TOA t_(i)and TOA of additional peaks t_(i,1) and t_(i,2), the additional peaksare represented by the relative time differences δ_(i,1)=t_(i,1)−t_(i)and δ_(0,2)=t_(i,2)−t_(i).

SUMMARY

There currently exists certain problem(s).

The effect of what the UE choses for trade-off between robustness tonoise and LOS detection can create highly uncertain measurements. Insome situations, with many hearable cells, it can be possible to acceptsome noise peaks since others might compensate for this. While in sparsecells with few cells, one would not afford to detect a noise peak sinceit may not be possible to accurately determine the position.

Further, the positioning algorithm in the network node might havedifferent capabilities of excluding measurement caused by noise peaks.While the multipath RSTD feedback has been agreed to be standardized,details on how to efficiently assist the UE on this report remainsunexplored.

Certain aspects of the present disclosure and their embodiments mayprovide solutions to these or other problems.

There is provided a method, executed in a target device, for providingObserved Time Difference of Arrival (OTDOA) Reference Signal TimeDifference (RSTD) measurements to a location server. The methodcomprises the step of sending, to the location server, an indication ofa capability to support OTDOA location measurements using multipathRSTD. The method also comprises the step of receiving a request forOTDOA location measurements using multipath RSTD, from the locationserver. The method further comprises the step of receiving assistancedata providing details of required OTDOA location measurements usingmultipath RSTD, from the location server. The method comprises the stepof receiving a signal from an RSTD reference cell and from a neighborcell and the step of observing a time difference between the receivedsignals thereby obtaining the required OTDOA location measurements usingmultipath RSTD. The method also comprises the step of sending therequired OTDOA location measurements using multipath RSTD to thelocation server.

There is provided a method, executed in a location server, for receivingObserved Time Difference of Arrival (OTDOA) Reference Signal TimeDifference (RSTD) measurements from a target device. The methodcomprises the step of receiving an indication of a capability to supportOTDOA location measurements using multipath RSTD, from the targetdevice. The method also comprises the step of sending a request forOTDOA location measurements using multipath RSTD, to the target device.The method further comprises the step of sending assistance dataproviding details of required OTDOA location measurements usingmultipath RSTD, to the target device, and the step of receiving therequired OTDOA location measurements using multipath RSTD, from thetarget device.

There is provided a wireless device operative to provide Observed TimeDifference of Arrival (OTDOA) Reference Signal Time Difference (RSTD)measurements to a location server. The wireless device comprisesprocessing circuitry and a memory, the memory containing instructionsexecutable by the processing circuitry whereby the wireless device isoperative to send, to the location server, an indication of a capabilityto support OTDOA location measurements using multipath RSTD. Thewireless device is also operative to receive a request for OTDOAlocation measurements using multipath RSTD, from the location server andto receive assistance data providing details of required OTDOA locationmeasurements using multipath RSTD, from the location server. Thewireless device is further operative to receive a signal from an RSTDreference cell and from a neighbor cell, to observe a time differencebetween the received signals thereby obtaining the required OTDOAlocation measurements using multipath RSTD, and to send the requiredOTDOA location measurements using multipath RSTD to the location server.

There is provided a location server operative to receive Observed TimeDifference of Arrival (OTDOA) Reference Signal Time Difference (RSTD)measurements from a wireless device, the location server comprisingprocessing circuitry and a memory, the memory containing instructionsexecutable by the processing circuitry whereby the location server isoperative to receive an indication of a capability to support OTDOAlocation measurements using multipath RSTD, from a wireless device. Thelocation server is also operative to send a request for OTDOA locationmeasurements using multipath RSTD, to the wireless device and to sendassistance data providing details of required OTDOA locationmeasurements using multipath RSTD, to the wireless device.

The location server is further operative to receive the required OTDOAlocation measurements using multipath RSTD, from the wireless device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a schematic illustration of the LTE positioning architecture.

FIG. 2 is a schematic illustration of two cells with two nodes and twoUEs according to an example.

FIG. 3 is a schematic illustration of OTDOA position estimation based onmultilateration on the RSTD measurements according to an example.

FIGS. 4a and 4b are graphs illustrating distance estimation based oncross correlation according to some examples.

FIG. 5 is a schematic illustration of peaks in positioning referencesignals according to an example.

FIG. 6 is a flowchart of a method according to an embodiment.

FIG. 7 is a flowchart of a method according to another embodiment.

FIG. 8 is a flowchart of a method according to another embodiment.

FIG. 9 is a flowchart of a method according to another embodiment.

FIG. 10 is a schematic illustration of a normalized profile delayprofile according to an example.

FIG. 11 is a graph illustrating probably of peak amplitudes for low andhigh a values according to an example.

FIG. 12 is a flowchart of a method according to another embodiment.

FIG. 13 is a flowchart of a method according to another embodiment.

FIG. 14a is a schematic illustration of a wireless network according toan embodiment.

FIG. 14b is a schematic illustration of a user equipment according to anembodiment.

FIG. 14c is a schematic illustration of a wireless device according toan embodiment.

FIG. 14d is a schematic illustration of a network node according to anembodiment.

FIG. 15 illustrates a virtualization environment in which functionsaccording to some embodiment(s) may be implemented.

DETAILED DESCRIPTION

Generally, all terms used herein are to be interpreted according totheir ordinary meaning in the technical field, unless explicitly definedotherwise herein. All references to “a/an/the element, apparatus,component, means, step, etc.” are to be interpreted openly as referringto at least one instance of the element, apparatus, component, means,step, etc., unless explicitly stated otherwise. The steps of any methoddisclosed herein do not have to be performed in the exact orderdisclosed, unless explicitly stated.

Various features and embodiments will now be described with reference tothe figures to fully convey the scope of the disclosure to those skilledin the art. Many aspects will be described in terms of sequences ofactions or functions. It should be recognized that in some embodiments,some functions or actions could be performed by specialized circuits, byprogram instructions being executed by one or more processors, or by acombination of both. Further, some embodiments can be partially orcompletely embodied in the form of computer-readable carrier or carrierwave containing an appropriate set of computer instructions that wouldcause a processor to carry out the techniques described herein. In somealternate embodiments, the functions/actions may occur out of the ordernoted in the sequence of actions or simultaneously. Furthermore, in someillustrations, some blocks, functions or actions may be optional and mayor may not be executed; these are generally illustrated with dashedlines.

According to an embodiment, a network node, such as a location server 2,can configure the UEs 1 with a probability-threshold or/and expectedmultipath measurement for different multipath scenarios in order toconsider a trade-off between LOS detection and robustness to noise.

In order to do so, support information may be sent from the network nodeto a receiver entity to support TOA estimation in possible multipathpropagation conditions. The receiver entity may be a UE 1 or a wirelessdevice, but can also be a receiver node, in more general terms, forexample a base station 3.

FIG. 6 illustrates a method 60 from a receiver entity perspective,according to an embodiment, comprising:

-   -   optionally, the receiver entity sends, to a network node, a        capability for multipath reporting and receiving a response,        step 61;    -   the receiver obtains, from the network node, support information        for Time of Arrival (TOA) estimation in possible multipath        propagation conditions, step 62;    -   the receiver entity receives a signal and estimates TOA        information based on the received signal and on the obtained        support information, step 63; and    -   the receiver entity either sends the TOA information to a        network node, or processes the TOA information, step 64.

The step of processing the TOA information 64 may be done locally in thewireless device.

FIG. 7 illustrates a method 70 from a network node perspective,according to an embodiment, comprising:

-   -   optionally, the network node obtains, from a receiver entity, a        capability for multipath reporting and provides a response, step        71;    -   the network node determines, in consideration of the receiver        entity, support information for TOA estimation in possible        multipath propagation conditions, step 72;    -   the network node sends the support information to the receiver        entity, step 73; and    -   the network node obtains location information from the receiver        entity, step 74.

Alternatively worded, there is provided a method 70, executed in anetwork node, comprising:

-   -   determining, in consideration of a wireless device, support        information for TOA estimation in possible multipath propagation        conditions, step 72;    -   sending the support information to the wireless device, step 73;        and    -   obtaining location information from the wireless device, step        74.

The method may further comprise obtaining, from the wireless device, acapability for multipath reporting and provides a response, step 71.

The steps of the above methods are described below and in more details.The support information sent to the target device in possible multipathpropagation scenarios, as well as the actions considered, can differ indifferent embodiments. In one embodiment, the network node signals anexpected multipath indication to the UE. When the indication is set toTRUE (or if interpreted as TRUE. e.g. in some context if the indicationis explicitly missing), the UE interpret this as an indication that itis likely that multipath propagation can be experienced. This cantrigger the UE to explicitly search for, detect and/or measureadditional peaks in a received signal. The indication can be given ingeneral, or in relation to one or more cells or reference signals or areceived packet or packets.

The network node can trigger the sending, to a first UE, of an expectedmultipath indication set to TRUE in cases comprising:

-   -   where there is historical information indicating that UEs        previously have reported multipath propagation and/or additional        peaks:        -   with the same serving node as the one serving the first UE;        -   with the same approximate location as the first UE, for            example with the same tracking area/location area/routing            area (information that associates the LIE to a set of cells,            nodes, reference signals) information as the first UE;        -   with at least one cell/node/reference signal in the            assistance data provided to UEs being the same as for the            first UE;    -   where there is historical information indicating that UEs        previously have been positioned with relatively poor accuracy:        -   for example determined by comparing positioning based on at            least two positioning methods, such as Global Navigation            Satellite System (GNSS) on the one hand and a TOA-based            method on the other;    -   according to deployment information of the node:        -   if the node is deployed in high scattering environment, for            example indoor, or in dense urban areas.

When the indication is set to FALSE (or if interpreted as FALSE. e.g. insome context if the indication is explicitly missing), the UE interpretthis as an indication that it is not likely that multipath propagationcan be experienced. This can trigger the UE to refrain from searchingfor, detect and/or measure additional peaks in a received signal. Theindication can be given in general, or in relation to one or more cellsor reference signals or a received packet or packets.

The network node can trigger the sending, to a first UE, of an expectedmultipath indication set to FALSE in cases comprising:

-   -   where there is historical information indicating that UEs        previously have not reported multipath propagation and/or        additional peaks:        -   with the same serving node as the one serving the first UE;        -   with the same approximate location as the first UE, for            example with the same tracking area/location area/routing            area (information that associates the UE to a set of cells,            nodes, reference signals) information as the first UE;        -   with at least one cell/node/reference signal in the            assistance data provided to UEs being the same as the first            UE;    -   where there is historical information indicating that UEs        previously have been positioned with relatively good accuracy        without considering information about additional peaks:        -   for example determined by comparing positioning based on at            least two positioning methods, such as GNSS, on the one            hand, and a TOA-based method on the other;    -   according to deployment information of the node:        -   if the node is deployed in low scattering environment, for            example in open outdoor areas.

FIG. 8 illustrates a method 80, from a UE perspective, according to anembodiment where the TOA support information is an expected multipathindication, comprising:

-   -   the UE obtains, from a network node, an expected multipath        indication, optionally in association one or more        cells/nodes/reference signals, step 81;    -   in case the indication is interpreted as TRUE, the UE triggers        search/detection/measurement for additional peaks of a        cell/node/reference signal, step 82;    -   in case the indication is interpreted as FALSE, the UE refrains        from searching/detecting/measuring additional peaks of a        cell/node/reference signal, step 83; and    -   the UE reports the location information, step 84.

Alternatively worded, FIG. 8 illustrates a method 80, executed in a UE,where the TOA support information is an expected multipath indication,comprising:

-   -   obtaining, from a network node, an expected multipath        indication, step 81;    -   if the indication is interpreted as TRUE, triggering        search/detection/measurement for additional peaks of a        cell/node/reference signal, step 82;    -   if the indication is interpreted as FALSE, refraining (not        triggering) from searching/detecting/measuring additional peaks        of a cell/node/reference signal, step 83; and    -   reporting the location information, step 84.

The method wherein in step 81, the multipath indication is inassociation one or more cells/nodes/reference signals.

The sequences below show an example signaling impact according to anembodiment.

-- ASN1START OTDOA-ReferenceCellInfo ::= SEQUENCE { physCellId INTEGER(0..503), cellGlobalId ECGI OPTIONAL, -- Need ON earfcnRefARFCN-ValueEUTRA OPTIONAL, -- Cond NotSameAsServ0 antennaPortConfigENUMERATED {ports1-or-2, ports4, ... } OPTIONAL, -- Cond NotSameAsServ1cpLength ENUMERATED { normal, extended, ... }, prsInfo PRS-InfoOPTIONAL, -- Cond PRS ..., [[ earfcnRef-v9a0 ARFCN-ValueEUTRA-v9a0OPTIONAL -- Cond NotSameAsServ2 ]], [[ tpId-r14 INTEGER (0..4095)OPTIONAL -- Need ON ]] ]], [[ expectedMultipathRef-v14 BOOLEAN OPTIONAL]] } -- ASN1STOP -- ASN1START OTDOA-NeighbourCellInfoList ::= SEQUENCE(SIZE (1..maxFreqLayers)) OF OTDOA-NeighbourFreqInfoOTDOA-NeighbourFreqInfo ::= SEQUENCE (SIZE (1..24)) OFOTDOA-NeighbourCellInfoElement OTDOA-NeighbourCellInfoElement ::=SEQUENCE { physCellId INTEGER (0..503), cellGlobalId ECGI OPTIONAL, --Need ON earfcn ARFCN-ValueEUTRA OPTIONAL, -- Cond NotSameAsRef0 cpLengthENUMERATED {normal, extended, ...} OPTIONAL, -- Cond NotSameAsRef1prsInfo PRS-Info OPTIONAL, -- Cond NotSameAsRef2 antennaPortConfigENUMERATED {ports-1-or-2, ports-4, ...} OPTIONAL, -- Cond NotsameAsRef3slotNumberOffset INTEGER (0..19) OPTIONAL, -- Cond NotSameAsRef4prs-SubframeOffset INTEGER (0..1279) OPTIONAL, -- Cond InterFreqexpectedRSTD INTEGER (0..16383), expectedRSTD-Uncertainty INTEGER(0..1023), ..., [[ earfcn-v9a0 ARFCN-ValueEUTRA-v9a0 OPTIONAL -- CondNotSameAsRef5 ]], [[ tpId-r14 INTEGER (0..4095) OPTIONAL, -- Need ONprs-only-tp-r14 ENUMERATED { true } OPTIONAL -- Cond TBS ]] , [[expectedMultipathNeighbour-v-14 BOOLEAN OPTIONAL ]] }maxFreqLayers INTEGER ::= 3 -- ASN1STOP

For TOA estimation, there is an important trade-off between Line ofSight (LOS) detection and robustness to noise. Given a received signal,the UE 1 can analyze the different peaks, where each peak is associatedto a value such as the received power, cross-correlation, etc. of thesignal in relation to a threshold, and consider peaks above thethreshold as valid peaks, and peaks under the threshold as noise peaks.Instead of using a threshold with a predetermined value, apeak-probability threshold can be used. A peak-probability thresholdcan, for example, be based on cell deployment data and the networkpositioning algorithm. The TOA estimate is then determined based on theidentified (valid) peaks, where a valid peak is a peak above theprobability threshold, and the TOA estimate can, for example, bedetermined as the first of the valid peaks.

FIG. 9 illustrates a method 90, from a UE perspective, according to anembodiment comprising:

-   -   the UE is configured by the network, or receives configuration        settings from a network node, to perform TOA estimation        including a peak-probability threshold, step 91;    -   the UE detects a signal and estimates the Noise Peak        Distribution (NPD), step 92;    -   the UE uses the peak-probability configuration and the NPD to        find valid peaks, step 93; and    -   the UE determines TOA based on the valid peaks and reports the        set of TOA to the network node, step 94.

Alternatively worded, FIG. 9 provides a method 90, executed in a UE,comprising:

-   -   receiving configuration settings from a network node, to perform        TOA estimation including a peak-probability threshold, step 91;    -   detecting a signal and estimating a Noise Peak Distribution        (NPD), step 92;    -   identifying valid peaks using the peak-probability configuration        and the NPD, step 93; and    -   determining TOA based on the valid peaks and reports the set of        TOA to the network node, step 94.

Step 91 may further comprise setting the peak-probability threshold to agiven value, where a higher threshold implies more or better robustnessto noise. The peak-probability may be configured in a network node andsignaled to the UE. The network node/UE can base the decision, i.e. theidentification of valid peaks, on the following:

-   -   Capabilities to exclude non-line of sight (NLOS) measurements        where a network node with capabilities might be able to exclude        erroneous measurement caused by a noise peak detection. That can        allow to set a lower probability threshold.    -   Cell deployment data given a rough position of the UE, e.g. the        location of the cell where it is connected, where the network        node can estimate the rough number of hearable cells for the UE,        if the number of cells is high. In this case, the network node        can use a lower threshold since this scenario typically provides        a few highly accurate measurements, in comparison with many bad        measurements that can be obtained with other scenarios.

In step 92, the Noise Peak Distribution (NPD) may comprise a probabilityof a peak being caused by noise. The NPD is for example based on thenoise window in FIG. 10, where a UE can estimate the variance (σ) of thenoise peak amplitudes given a normalized Profile Delay Profile (PDP).The NDP can then be modelled using a Rice-distribution with theestimated a if the noise properties are circular complex Gaussian. Twoexamples of NPDs are shown in FIG. 11, first an NDP from a cell withhigh Signal to noise ratio (SNR) (i.e. low σ), and secondly from a cellwith low SNR (high σ). Also, the NDP can be made by directly creating aCumulative Density Function (CDF) based on the peaks in the noisewindow.

In Step 93, the probability-threshold and the peak distribution may beused to find the valid peaks inside the search window illustrated inFIG. 10. For example, based on FIG. 10, if a search window peak has anamplitude of 0.4, for a high σ, FIG. 11 shows a 20% probability that itis a noise peak, or in other words, 80% chance that it is a peak causedby one path of the received signal. While for the low σ, the probabilityis very low that it is a noise peak or very high that the peak is causedby one path of the received signal. This information thus allows thereceiver to trade-off between the robustness to LOS detection and noisesuppression.

In step 94, based on the valid peaks from FIG. 10, the UE picks one ofthe valid peaks as the TOA estimate, for example the first of the validpeaks may be selected. In another embodiment, the UE may pick two ormore of the valid peaks or it may pick another valid peak based onanother criterion. The UE then reports the TOA to the network node, oras in LTE, the Reference Signal Time Difference (RSTD) measurements. Inyet another embodiment, the UE may report in the form of a multipathRSTD report as described further above in the introductory part of thisspecification, when it detects two or more valid peaks per cell.Additionally, the UE may also report the probability information of thedetected peak(s).

The sequences below show an example signaling impact according to anembodiment.

-- ASN1START OTDOA-ReferenceCellInfo ::= SEQUENCE { physCellId INTEGER(0..503), cellGlobalId ECGI OPTIONAL, -- Need ON earfcnRefARFCN-ValueEUTRA OPTIONAL, -- Cond NotSameAsServ0 antennaPortConfigENUMERATED {ports1-or-2, ports4, ... } OPTIONAL, -- Cond NotSameAsServ1cpLength ENUMERATED { normal, extended, ... }, prsInfo PRS-InfoOPTIONAL, -- Cond PRS ..., [[ earfcnRef-v9a0 ARFCN-ValueEUTRA-v9a0OPTIONAL -- Cond NotSameAsServ2 ]], [[ tpId-r14 INTEGER (0..4055)OPTIONAL -- Need ON ]] ]], [[ [[ peakDetectionThresReference-v14 INTEGER(0..NN) OPTIONAL -- Need ON ]] } -- ASN1STOP -- ASNISTARTOTDOA-NeighbourCellInfoList ::= SEQUENCE (SIZE (1..waxFreqLayers)) OFOTDOA-NeighbourFreqInfo OTDOA-NeighbourFreqInfo ::= SEQUENCE (SIZE (1..24)) OF OTDOA-NeighbourCellInfoElement OTDOA-NeighbourCellInfoElement::= SEQUENCE { physCellId INTEGER (0..503), cellGlobalId ECGI OPTIONAL,-- Need ON earfcn ARFCN-ValueEUTRA OPTIONAL, -- Cond NotSameAsRef0cpLength ENUMERATED {normal, extended, ...} OPTIONAL, -- CondNotSameAsRef1 prsInfo PRS-Info OPTIONAL, -- Cond NotSameAsRef2antennaPortConfig ENUMERATED {ports-1-or-2, ports-4, ...} OPTIONAL, --Cond NotsameAsRef3 slotNumberOffset INTEGER (0..19) OPTIONAL, -- CondNotSameAsRef4 prs-SubframeOffset INTEGER (0..1279) OPTIONAL, -- CondInterFreq expectedRSTD INTEGER (0..1638), expectedRSTD-UncertaintyINTEGER (0..1023), ..., [[ earfcn-v9a0 ARFCN-ValueEUTRA-v9a0 OPTIONAL --Cond NotSameAsRef5 ]], [[ tpId-r14 INTEGER (0..4095) OPTIONAL, -- NeedON prs-only-tp-r14 ENUMERATED { true } OPTIONAL -- Cond TBS ]], [[peakDetectionThresNeighbour-v14 INTEGER (0..NN) OPTIONAL -- Need ON ]] }maxFreqLayers INTEGER ::= 3 -- ASN1STOP

FIG. 12 illustrates a method 120, which includes some rearrangements ofsteps and elements previously described. The method 120 is executed in atarget device, for providing Observed Time Difference of Arrival (OTDOA)Reference Signal Time Difference (RSTD) measurements to a locationserver. The method 120 comprises the steps of:

-   -   sending, step 121, to the location server, an indication of a        capability to support OTDOA location measurements using        multipath RSTD;    -   receiving, step 122, a request for OTDOA location measurements        using multipath RSTD, from the location server;    -   receiving, step 123, assistance data providing details of        required OTDOA location measurements using multipath RSTD, from        the location server;    -   receiving, step 124, a signal from an RSTD reference cell and        from a neighbor cell;    -   observing a time difference, step 125, between the received        signals thereby obtaining the required OTDOA location        measurements using multipath RSTD; and    -   sending, step 126, the required OTDOA location measurements        using multipath RSTD to the location server.

In the method, the neighbor cell for which the time difference is to beobserved may be indicated by the location server in the assistance data.The assistance data may contain an indication that triggers the targetdevice to search for additional peaks in at least one received signal.The location server may trigger the execution of the method based onhistorical information indicating that the target device has previouslyreported measurements using multipath RSTD. The location server mayalternatively trigger the execution of the method based on historicalinformation indicating that the target device has previously beenpositioned with poor accuracy. The target device may have previouslybeen positioned based on at least two positioning methods such as GlobalNavigation Satellite System (GNSS) and OTDOA RSTD. The step 125 ofobserving may further comprise using a peak-probability threshold of agiven value to estimate the OTDOA location measurements using multipathRSTD, where a higher threshold provides better robustness to noise. Thetarget device may be operative to exclude non-line of sight (NLOS) OTDOAlocation measurements, thereby allowing to set a lower peak-probabilitythreshold. The peak-probability may be configured by the location serverand may be provided to the target device. The peak-probability thresholdmay be based on cell deployment data and a network positioningalgorithm, the OTDOA location measurements using multipath RSTD may bebased on identified valid peaks of signals from the reference andneighbor cells, a valid peak may be a peak above the peak-probabilitythreshold, and the OTDOA location measurements using multipath RSTD maybe determined as the firsts of the valid peaks from the reference andneighbor cells.

FIG. 13 illustrates a method 130, which includes some rearrangements ofsteps and elements previously described. The method 130 is executed in alocation server, for receiving Observed Time Difference of Arrival(OTDOA) Reference Signal Time Difference (RSTD) measurements from atarget device. The method 130 comprises the steps of:

-   -   receiving, step 131, an indication of a capability to support        OTDOA location measurements using multipath RSTD, from the        target device;    -   sending, step 132, a request for OTDOA location measurements        using multipath RSTD, to the target device;    -   sending, step 133, assistance data providing details of required        OTDOA location measurements using multipath RSTD, to the target        device; and    -   receiving, step 134, the required OTDOA location measurements        using multipath RSTD, from the target device.

The location server may indicate in the assistance data a neighbor cellfor which a time difference is to be observed by the target device. Thelocation server may trigger the target device to search for additionalpeaks in at least one received signal through an indication in theassistance data. The location server may trigger the execution of themethod based on historical information indicating that the target devicehas previously reported measurements using multipath RSTD. The locationserver may alternatively trigger the execution of the method based onhistorical information indicating that the target device has previouslybeen positioned with poor accuracy. The target device may havepreviously been positioned based on at least two positioning methodssuch as Global Navigation Satellite System (GNSS) and OTDOA RSTD. Thelocation server may provide a peak-probability threshold of a givenvalue to the target device for estimation of the OTDOA locationmeasurements using multipath RSTD, where a higher threshold providesbetter robustness to noise. The peak-probability threshold may be basedon cell deployment data and a network positioning algorithm, the OTDOAlocation measurements using multipath RSTD may be based on identifiedvalid peaks of signals from the reference and neighbor cells, a validpeak may be a peak above the peak-probability threshold, and the OTDOAlocation measurements using multipath RSTD may be determined as thefirsts of the valid peaks.

There is provided an apparatus/network node comprising processingcircuitry and a memory, the memory containing instructions executable bythe processing circuitry whereby the apparatus is operative to executemethods related to apparatus/network node embodiments; this is describedin more details further below.

There is provided a wireless device (WD) or User Equipment (UE)comprising processing circuitry and a memory, the memory containinginstructions executable by the processing circuitry whereby the WD or UEis operative to execute the methods related to WD/UE embodiments; thisis described in more details further below.

Computer programs and computer-readable media configured to storeinstructions for executing steps according to embodiments of methodsdisclosed herein are also provided.

Certain embodiments may provide one or more of the following technicaladvantage(s).

The advantages include better and/or more efficient positioning due tothe following:

-   -   improved configurability since the network node can configure        the peak-probability threshold based on network deployment data,        positioning algorithm complexity, etc.;    -   the receiver entity can plan when efforts to detect additional        paths matter or not.

It is to be noted that any feature of any of the embodiments disclosedherein may be applied to any other embodiment, wherever appropriate.Likewise, any advantage of any of the embodiments may apply to the otherembodiments, and vice versa. Certain embodiments may have some, or noneof the above advantages. Other advantages will be apparent to persons ofordinary skill in the art. Other objectives, features and advantages ofthe enclosed embodiments will be apparent from the followingdescription.

Although the solutions described above may be implemented in anyappropriate type of system using any suitable components, particularembodiments of the described solutions may be implemented in a wirelessnetwork such as the example wireless communication network illustratedin FIG. 14a . In the example of FIG. 14a , the wireless communicationnetwork provides communication and other types of services to one ormore wireless devices. The wireless communication network includes oneor more instances of network nodes that facilitate the wireless devices'access to and/or use of the services provided by the wirelesscommunication network. The wireless communication network may furtherinclude any additional elements suitable to support communicationbetween wireless devices or between a wireless device and anothercommunication device, such as a landline telephone.

Network 1410 may comprise one or more IP networks, public switchedtelephone networks (PSTNs), packet data networks, optical networks, widearea networks (WANs), local area networks (LANs), wireless local areanetworks (WLANs), wired networks, wireless networks, metropolitan areanetworks, and other networks to enable communication between devices.

The wireless communication network may represent any type ofcommunication, telecommunication, data, cellular, and/or radio networkor other type of system. In particular embodiments, the wirelesscommunication network may be configured to operate according to specificstandards or other types of predefined rules or procedures. Thus,particular embodiments of the wireless communication network mayimplement communication standards, such as Global System for MobileCommunications (GSM), Universal Mobile Telecommunications System (UMTS),Long Term Evolution (LTE), and/or other suitable 2G, 3G, 4G, 5G or NRstandards; wireless local area network (WLAN) standards, such as theIEEE 802.11 standards; and/or any other appropriate wirelesscommunication standard, such as the Worldwide Interoperability forMicrowave Access (WiMax), Bluetooth, and/or ZigBee standards.

FIG. 14a illustrates a wireless network comprising a network node 1440and wireless device (WD) 140, in accordance with a particularembodiment. For simplicity, FIG. 14a only depicts network 1410, networknodes 1440 and 1420, and WD 140. Network node 1440 comprises processor1442, storage 1443, interface 1441, and antenna 1430. Similarly, WD 140comprises processor 142, storage 145, interface 143 and antenna 147.These components may work together in order to provide network nodeand/or wireless device functionality, such as providing wirelessconnections in a wireless network. In different embodiments, thewireless network may comprise any number of wired or wireless networks,network nodes, such as the location server described previously, basestations, controllers, wireless devices, relay stations, and/or anyother components that may facilitate or participate in the communicationof data and/or signals whether via wired or wireless connections.

As used herein, “network node” refers to equipment capable, configured,arranged and/or operable to communicate directly or indirectly with awireless device and/or with other equipment in the wirelesscommunication network that enable and/or provide wireless access to thewireless device. Examples of network nodes include, but are not limitedto, access points (APs), in particular radio access points. A networknode may represent base stations (BSs), such as radio base stations.Particular examples of radio base stations include Node Bs, and evolvedNode Bs (eNBs). Base stations may be categorized based on the amount ofcoverage they provide (or, stated differently, their transmit powerlevel) and may then also be referred to as femto base stations, picobase stations, micro base stations, or macro base stations. “Networknode” also includes one or more (or all) parts of a distributed radiobase station such as centralized digital units and/or remote radio units(RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remoteradio units may or may not be integrated with an antenna as an antennaintegrated radio. Parts of a distributed radio base stations may also bereferred to as nodes in a distributed antenna system (DAS).

“Network node” includes nodes that are located outside as well as insidebuildings or structures. In some instances, structures may causedegradation of the signals or even partially or totally block signalpropagation.

As a particular non-limiting example, a base station may be a relay nodeor a relay donor node controlling a relay.

Yet further examples of network nodes include multi-standard radio (MSR)radio equipment such as MSR BSs, network controllers such as radionetwork controllers (RNCs) or base station controllers (BSCs), basetransceiver stations (BTSs), transmission points, transmission nodes,Multi-cell/multicast Coordination Entities (MCEs), core network nodes(e.g., MSCs, MMEs), O&M nodes, OSS nodes, SON nodes, positioning nodes(e.g., E-SMLCs), and/or MDTs. More generally, however, network nodes mayrepresent any suitable device (or group of devices) capable, configured,arranged, and/or operable to enable and/or provide a wireless deviceaccess to the wireless communication network or to provide some serviceto a wireless device that has accessed the wireless communicationnetwork. Accordingly, in the present case, network node can representthe location server.

As used herein, the term “radio node” is used generically to refer bothto wireless devices and network nodes, as each is respectively describedabove.

In FIG. 14a , Network node 1440 comprises processor 1442, storage 1443,interface 1441, and antenna 1430. These components are depicted assingle boxes located within a single larger box. In practice, however, anetwork node may comprise multiple different physical components thatmake up a single illustrated component (e.g., interface 1441 maycomprise terminals for coupling wires for a wired connection and a radiotransceiver for a wireless connection). As another example, network node1440 may be a virtual network node in which multiple differentphysically separate components interact to provide the functionality ofnetwork node 1440 (e.g., processor 1442 may comprise three separateprocessors located in three separate enclosures, where each processor isresponsible for a different function for a particular instance ofnetwork node 1440). Similarly, network node 1440 may be composed ofmultiple physically separate components (e.g., a NodeB component and aRNC component, a BTS component and a BSC component, etc.), which mayeach have their own respective processor, storage, and interfacecomponents. In certain scenarios in which network node 1440 comprisesmultiple separate components (e.g., BTS and BSC components), one or moreof the separate components may be shared among several network nodes.For example, a single RNC may control multiple NodeB's. In such ascenario, each unique NodeB and BSC pair, may be a separate networknode. In some embodiments, network node 1440 may be configured tosupport multiple radio access technologies (RATs). In such embodiments,some components may be duplicated (e.g., separate storage 1443 for thedifferent RATs) and some components may be reused (e.g., the sameantenna 1430 may be shared by the RATs).

Processor 1442 may be a combination of one or more of a microprocessor,controller, microcontroller, central processing unit, digital signalprocessor, application-specific integrated circuits, field programmablegate array, or any other suitable computing device, resource, orcombination of hardware, software and/or encoded logic operable toprovide, either alone or in conjunction with other network node 1440components, such as storage 1443, network node 1440 functionality. Forexample, processor 1442 may execute instructions stored in storage 1443.Such functionality may include providing various wireless featuresdiscussed herein to a wireless device, such as WD 140, including any ofthe features or benefits disclosed herein.

Storage 1443 may comprise any form of volatile or non-volatile computerreadable memory including, without limitation, persistent storage,solid-state memory, remotely mounted memory, magnetic media, opticalmedia, random access memory (RAM), read-only memory (ROM), removablemedia, or any other suitable local or remote memory component. Storage1443 may store any suitable instructions, data or information, includingsoftware and encoded logic, utilized by network node 1440. Storage 1443may be used to store any calculations made by processor 1442 and/or anydata received via interface 1441.

Network node 1440 also comprises interface 1441 which may be used in thewired or wireless communication of signalling and/or data betweennetwork node 1440, network 1410, and/or WD 140. For example, interface1441 may perform any formatting, coding, or translating that may beneeded to allow network node 1440 to send and receive data from network1410 over a wired connection. Interface 1441 may also include a radiotransmitter and/or receiver that may be coupled to or a part of antenna1430. The radio may receive digital data that is to be sent out to othernetwork nodes or WDs via a wireless connection. The radio may convertthe digital data into a radio signal having the appropriate channel andbandwidth parameters. The radio signal may then be transmitted viaantenna 1430 to the appropriate recipient (e.g., WD 140).

Antenna 1430 may be any type of antenna capable of transmitting andreceiving data and/or signals wirelessly. In some embodiments, antenna1430 may comprise one or more omni-directional, sector or panel antennasoperable to transmit/receive radio signals between, for example, 2 GHzand 66 GHz. An omni-directional antenna may be used to transmit/receiveradio signals in any direction, a sector antenna may be used totransmit/receive radio signals from devices within a particular area,and a panel antenna may be a line of sight antenna used totransmit/receive radio signals in a relatively straight line.

Network node 1440 may perform steps or functions described herein inrelation with some embodiments.

As such, the network node may by a location server operative to receiveObserved Time Difference of Arrival (OTDOA) Reference Signal TimeDifference (RSTD) measurements from a target, wireless, device, thelocation server comprising processing circuitry and a memory, the memorycontaining instructions executable by the processing circuitry wherebythe location server is operative to:

-   -   receive an indication of a capability to support OTDOA location        measurements using multipath RSTD, from a wireless device;    -   send a request for OTDOA location measurements using multipath        RSTD, to the wireless device;    -   send assistance data providing details of required OTDOA        location measurements using multipath RSTD, to the wireless        device; and    -   receive the required OTDOA location measurements using multipath        RSTD, from the wireless device.

The location server may indicate in the assistance data a neighbor cellfor which a time difference is to be observed by the target device. Thelocation server may trigger the target device to search for additionalpeaks in at least one received signal through an indication in theassistance data. The location server may trigger the execution of themethod based on historical information indicating that the target devicehas previously reported measurements using multipath RSTD. The locationserver may alternatively trigger the execution of the method based onhistorical information indicating that the target device has previouslybeen positioned with poor accuracy. The target device may havepreviously been positioned based on at least two positioning methodssuch as Global Navigation Satellite System (GNSS) and OTDOA RSTD. Thelocation server may provide a peak-probability threshold of a givenvalue to the target device for estimation of the OTDOA locationmeasurements using multipath RSTD, where a higher threshold providesbetter robustness to noise. The peak-probability threshold may be basedon cell deployment data and a network positioning algorithm, the OTDOAlocation measurements using multipath RSTD may be based on identifiedvalid peaks of signals from the reference and neighbor cells, a validpeak may be a peak above the peak-probability threshold, and the OTDOAlocation measurements using multipath RSTD may be determined as thefirsts of the valid peaks.

As used herein, “wireless device” (WD) refers to a device capable,configured, arranged and/or operable to communicate wirelessly withnetwork nodes and/or another wireless device. In this disclosure, thewireless device is sometimes alternatively called target device.Communicating wirelessly may involve transmitting and/or receivingwireless signals using electromagnetic signals, radio waves, infraredsignals, and/or other types of signals suitable for conveyinginformation through air. In particular embodiments, wireless devices maybe configured to transmit and/or receive information without directhuman interaction. For instance, a wireless device may be designed totransmit information to a network on a predetermined schedule, whentriggered by an internal or external event, or in response to requestsfrom the network. Generally, a wireless device may represent any devicecapable of, configured for, arranged for, and/or operable for wirelesscommunication, for example radio communication devices. Examples ofwireless devices include, but are not limited to, user equipment (UE)such as smart phones. Further examples include wireless cameras,wireless-enabled tablet computers, laptop-embedded equipment (LEE),laptop-mounted equipment (LME), USB dongles, and/or wirelesscustomer-premises equipment (CPE).

As one specific example, a wireless device may represent a UE configuredfor communication in accordance with one or more communication standardspromulgated by the 3^(rd) Generation Partnership Project (3GPP), such as3GPP's GSM. UMTS, LTE, and/or 5G standards. As used herein, a “userequipment” or “UE” may not necessarily have a “user” in the sense of ahuman user who owns and/or operates the relevant device. Instead, a UEmay represent a device that is intended for sale to, or operation by, ahuman user but that may not initially be associated with a specifichuman user.

The wireless device may support device-to-device (D2D) communication,for example by implementing a 3GPP standard for sidelink communication,and may in this case be referred to as a D2D communication device.

As yet another specific example, in an Internet of Things (IOT)scenario, a wireless device may represent a machine or other device thatperforms monitoring and/or measurements, and transmits the results ofsuch monitoring and/or measurements to another wireless device and/or anetwork node. The wireless device may in this case be amachine-to-machine (M2M) device, which may in a 3GPP context be referredto as a machine-type communication (MTC) device. As one particularexample, the wireless device may be a UE implementing the 3GPP narrowband internet of things (NB-IoT) standard. Particular examples of suchmachines or devices are sensors, metering devices such as power meters,industrial machinery, or home or personal appliances, e.g.refrigerators, televisions, personal wearables such as watches etc. Inother scenarios, a wireless device may represent a vehicle or otherequipment that is capable of monitoring and/or reporting on itsoperational status or other functions associated with its operation.

A wireless device as described above may represent the endpoint of awireless connection, in which case the device may be referred to as awireless terminal. Furthermore, a wireless device as described above maybe mobile, in which case it may also be referred to as a mobile deviceor a mobile terminal.

As depicted in FIG. 14a , WD 140 may be any type of wireless endpoint,mobile station, mobile phone, wireless local loop phone, smartphone,user equipment, desktop computer, PDA, cell phone, tablet, laptop, VoIPphone or handset, vehicle, or other device which is able to wirelesslysend and receive data and/or signals to and from a network node, such asnetwork node 1440 and/or other WDs. WD 140 comprises processor 142,storage 145, interface 143, and antenna 147. Like network node 1440, thecomponents of WD 140 are depicted as single boxes located within asingle larger box, however, in practice a wireless device may comprisemultiple different physical components that make up a single illustratedcomponent (e.g., storage 145 may comprise multiple discrete microchips,each microchip representing a portion of the total storage capacity).Processor 142 may be a combination of one or more of a microprocessor,controller, microcontroller, central processing unit, digital signalprocessor, application-specific integrated circuits, field programmablegate array, or any other suitable computing device, resource, orcombination of hardware, software and/or encoded logic operable toprovide, either alone or in combination with other WD 140 components,such as storage 145, WD 140 functionality. Such functionality mayinclude providing various wireless features discussed herein, includingany of the features or benefits disclosed herein.

Storage 145 may be any form of volatile or non-volatile memoryincluding, without limitation, persistent storage, solid-state memory,remotely mounted memory, magnetic media, optical media, random accessmemory (RAM), read-only memory (ROM), removable media, or any othersuitable local or remote memory component. Storage 145 may store anysuitable data, instructions, or information, including software andencoded logic, utilized by WD) 140. Storage 145 may be used to store anycalculations made by processor 142 and/or any data received viainterface 143. Storage 145 may comprise computer-readable means on whicha computer program can be stored. The computer program may includeinstructions which cause processor 142 (and any operatively coupledentities and devices, such as interface 143 and storage 145) to executemethods according to embodiments described herein. The computer programand/or computer program product may thus provide means for performingany steps herein disclosed.

Wireless device 140 may perform steps or functions described herein inrelation with some embodiments.

Interface 143 may be used in the wireless communication of signalingand/or data between WD 140 and network node 1440. For example, interface143 may perform any formatting, coding, or translating that may beneeded to allow WD 140 to send and receive data from network node 1440over a wireless connection. Interface 143 may also include a radiotransmitter and/or receiver that may be coupled to or a part of antenna147. The radio may receive digital data that is to be sent out tonetwork node 1440 via a wireless connection. The radio may convert thedigital data into a radio signal having the appropriate channel andbandwidth parameters. The radio signal may then be transmitted viaantenna 147 to network node 1440.

Antenna 147 may be any type of antenna capable of transmitting andreceiving data and/or signals wirelessly. In some embodiments, antenna147 may comprise one or more omni-directional, sector or panel antennasoperable to transmit/receive radio signals between 2 GHz and 66 GHz. Forsimplicity, antenna 147 may be considered a part of interface 143 to theextent that a wireless signal is being used.

The wireless device 140 as described above is operative to provideObserved Time Difference of Arrival (OTDOA) Reference Signal TimeDifference (RSTD) measurements to a location server, the wireless devicecomprising processing circuitry and a memory, the memory containinginstructions executable by the processing circuitry whereby the wirelessdevice is operative to:

-   -   send, to the location server, an indication of a capability to        support OTDOA location measurements using multipath RSTD;    -   receive a request for OTDOA location measurements using        multipath RSTD, from the location server;    -   receive assistance data providing details of required OTDOA        location measurements using multipath RSTD, from the location        server;    -   receive a signal from an RSTD reference cell and from a neighbor        cell;    -   observe a time difference between the received signals thereby        obtaining the required OTDOA location measurements using        multipath RSTD; and    -   send the required OTDOA location measurements using multipath        RSTD to the location server.

The neighbor cell for which the time difference is to be observed may beindicated by the location server in the assistance data. The assistancedata may contain an indication that triggers the wireless device tosearch for additional peaks in at least one received signal. Theexecution of the method may be triggered by the location server based onhistorical information indicating that the wireless device haspreviously reported measurements using multipath RSTD. The execution ofthe method may alternatively be triggered by the location server basedon historical information indicating that the wireless device haspreviously been positioned with poor accuracy. The wireless device mayhave previously been positioned based on at least two positioningmethods such as Global Navigation Satellite System (GNSS) and OTDOARSTD. The wireless device may further be operative to observe the timedifference using a peak-probability threshold of a given value toestimate the OTDOA location measurements using multipath RSTD, where ahigher threshold provides better robustness to noise. The wirelessdevice may be further operative to exclude non-line of sight (NLOS)OTDOA location measurements, thereby allowing to set a lowerpeak-probability threshold. The peak-probability may be configured bythe location server and may be provided to the wireless device. Thepeak-probability threshold may also be based on cell deployment data anda network positioning algorithm, the OTDOA location measurements usingto multipath RSTD may be based on identified valid peaks of signals fromthe reference and neighbor cells, a valid peak may be a peak above thepeak-probability threshold, and the OTDOA location measurements usingmultipath RSTD may be determined as the firsts of the valid peaks fromthe reference and neighbor cells.

The wireless network illustrated in FIG. 14a may include a plurality ofwireless devices 140 and a plurality of radio access nodes 1420, 1440,connected to one or more core network nodes (not illustrated) via anetwork 1410. Wireless devices 140 within a coverage area may each becapable of communicating directly with radio access nodes 1420, 1440over a wireless interface. In certain embodiments, wireless devices mayalso be capable of communicating with each other via device-to-device(D2D) communication. In certain embodiments, radio access nodes 1420,1440 may also be capable of communicating with each other, e.g. via aninterface (e.g. X2 in LTE).

In some embodiments, an area of wireless signal coverage associated witha radio access node 1420, 1440 may be referred to as a cell. A wirelessdevice 140 may be configured to operate in carrier aggregation (CA)implying aggregation of two or more carriers in at least one of DL andUL directions. With CA, a wireless device 140 can have multiple servingcells, wherein the term ‘serving’ herein means that the wireless device140 is configured with the corresponding serving cell and may receivefrom and/or transmit data to the network node on the serving cell e.g.on PCell or any of the SCells. The data is transmitted or received viaphysical channels e.g. PDSCH in DL, PUSCH in UL, etc. A componentcarrier (CC) also interchangeably called as carrier or aggregatedcarrier, PCC or SCC is configured at the wireless device 140 by thenetwork node 1440 using higher layer signaling e.g. by sending RRCconfiguration message to the wireless device 140. The configured CC isused by the network node 1440 for serving the wireless device 140 on theserving cell (e.g. on PCell, PSCell, SCell, etc.) of the configured CC.The configured CC is also used by the wireless device 140 for performingone or more radio measurements (e.g. RSRP, RSRQ, etc.) on the cellsoperating on the CC e.g. PCell, SCell or PSCell and neighboring cells.

The term SRS used herein may refer to any type of reference signal (RS)or more generally physical radio signals transmitted by the wirelessdevice 140 in the UL to enable the network node 1440 to determine the ULsignal quality e.g. UL SNR, SINR, etc. Examples of such referencesignals are sounding reference signals, DMRS, wireless device specificreference or pilot signals, etc. The embodiments are applicable to anytype of RS i.e. switching of carrier transmitting any type of RS.

In certain embodiments, radio access nodes 1420, 1440 may interface witha radio network controller. The radio network controller may controlradio access nodes 1420, 1440 and may provide certain radio resourcemanagement functions, mobility management functions, and/or othersuitable functions. In certain embodiments, the functions of the radionetwork controller may be included in radio access node 1420, 1440. Theradio network controller may interface with a core network node (notillustrated). In certain embodiments, the radio network controller mayinterface with the core network node via an interconnecting network1410.

The interconnecting network 1410 may refer to any interconnecting systemcapable of transmitting audio, video, signals, data, messages, or anycombination of the preceding. The interconnecting network 1410 mayinclude all or a portion of a public switched telephone network (PSTN),a public or private data network, a local area network (LAN), ametropolitan area network (MAN), a wide area network (WAN), a local,regional, or global communication or computer network such as theInternet, a wireline or wireless network, an enterprise intranet, or anyother suitable communication link, including combinations thereof.

In some embodiments, a core network node may manage the establishment ofcommunication sessions and various other functionalities for wirelessdevices 147. Examples of core network node may include MSC, MME, SGW,PGW, O&M, OSS, SON, positioning node (e.g. E-SMLC), MDT node, etc.Wireless devices 140 may exchange certain signals with the core networknode using the non-access stratum layer. In non-access stratumsignaling, signals between wireless devices 140 and the core networknode may be transparently passed through the radio access network. Incertain embodiments, radio access nodes 1420, 1440 may interface withone or more network nodes over an internode interface.

The embodiments may be implemented in any appropriate type oftelecommunication system supporting any suitable communication standardsand using any suitable components, and are applicable to any radioaccess technology (RAT) or multi-RAT systems in which the wirelessdevice receives and/or transmits signals (e.g., data). While certainembodiments are described for NR, 5G, 4G and/or LTE, the embodiments maybe applicable to any RAT, such as UTRA, E-UTRA, narrow band internet ofthings (NB-IoT), WiFi, Bluetooth, next generation RAT (NR, NX), 4G, 5G,LTE FDD/TDD, WCDMA/HSPA, GSM/GERAN, WLAN, CDMA2000, etc.

Turning to FIG. 14b , the wireless device 140 may be a user equipment.Wireless device 140 includes an antenna 147, radio front-end circuitry148, processing circuitry 142, and a computer-readable storage medium145. Antenna 147 may include one or more antennas or antenna arrays, andis configured to send and/or receive wireless signals, and is connectedto radio front-end circuitry 148. In certain alternative embodiments,wireless device 140 may not include antenna 147, and antenna 147 mayinstead be separate from wireless device 140 and be connectable towireless device 140 through an interface or port.

The radio front-end circuitry 148 may comprise various filters andamplifiers, is connected to antenna 147 and processing circuitry 142,and is configured to condition signals communicated between antenna 147and processing circuitry 142. In certain alternative embodiments,wireless device 140 may not include radio front-end circuitry 148, andprocessing circuitry 142 may instead be connected to antenna 147 withoutradio front-end circuitry 148.

Processing circuitry 142 may include one or more of radio frequency (RF)transceiver circuitry, baseband processing circuitry, and applicationprocessing circuitry. In some embodiments, the RF transceiver circuitry,baseband processing circuitry, and application processing circuitry maybe on separate chipsets. In alternative embodiments, part or all of thebaseband processing circuitry and application processing circuitry maybe combined into one chipset, and the RF transceiver circuitry may be ona separate chipset. In still alternative embodiments, part or all of theRF transceiver circuitry and baseband processing circuitry may be on thesame chipset, and the application processing circuitry may be on aseparate chipset. In yet other alternative embodiments, part or all ofthe RF transceiver circuitry, baseband processing circuitry, andapplication processing circuitry may be combined in the same chipset.Processing circuitry 142 may include, for example, one or more centralprocessing units (CPUs), one or more microprocessors, one or moreapplication-specific integrated circuits (ASICs), and/or one or morefield programmable gate arrays (FPGAs).

In particular embodiments, some or all of the functionality describedherein as being provided by a wireless device may be provided by theprocessing circuitry 142 executing instructions stored on acomputer-readable storage medium 145. In alternative embodiments, someor all of the functionality may be provided by the processing circuitry142 without executing instructions stored on a computer-readable medium,such as in a hard-wired manner. In any of those particular embodiments,whether executing instructions stored on a computer-readable storagemedium or not, the processing circuitry can be said to be configured toperform the described functionality. The benefits provided by suchfunctionality are not limited to the processing circuitry 142 alone orto other components of wireless device 140, but are enjoyed by thewireless device as a whole, and/or by end users and the wireless networkgenerally.

Antenna 147, radio front-end circuitry 148, and/or processing circuitry142 may be configured to perform any receiving operations describedherein as being performed by a wireless device. Any information, dataand/or signals may be received from a network node and/or anotherwireless device.

The processing circuitry 142 may be configured to perform any operationsdescribed herein as being performed by a wireless device. Operationsperformed by processing circuitry 142 may include processing informationobtained by the processing circuitry 142 by, for example, converting theobtained information into other information, comparing the obtainedinformation or converted information to information stored in thewireless device, and/or performing one or more operations based on theobtained information or converted information, and as a result of saidprocessing making a determination.

Antenna 147, radio front-end circuitry 148, and/or processing circuitry142 may be configured to perform any transmitting operations describedherein as being performed by a wireless device. Any information, dataand/or signals may be transmitted to a network node and/or anotherwireless device.

Computer-readable storage medium 145 is generally operable to storeinstructions, such as a computer program, software, an applicationincluding one or more of logic, rules, code, tables, etc. and/or otherinstructions capable of being executed by a processor. Examples ofcomputer-readable storage medium 145 include computer memory (forexample, Random Access Memory (RAM) or Read Only Memory (ROM)), massstorage media (for example, a hard disk), removable storage media (forexample, a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or anyother volatile or non-volatile, non-transitory computer-readable and/orcomputer-executable memory devices that store information, data, and/orinstructions that may be used by processing circuitry 142. In someembodiments, processing circuitry 142 and computer-readable storagemedium 145 may be considered to be integrated.

Alternative embodiments of wireless device or UE 140 may includeadditional components beyond those shown in FIG. 14b that may beresponsible for providing certain aspects of the wireless device'sfunctionality, including any of the functionality described hereinand/or any functionality necessary to support the solution describedabove. As just one example, wireless device 140 may include inputinterfaces, devices and circuits, and output interfaces, devices andcircuits. Input interfaces, devices, and circuits are configured toallow input of information into wireless device 140, and are connectedto processing circuitry 142 to allow processing circuitry 142 to processthe input information. For example, input interfaces, devices, andcircuits may include a microphone, a proximity or other sensor,keys/buttons, a touch display, one or more cameras, a USB port, or otherinput elements. Output interfaces, devices, and circuits are configuredto allow output of information from wireless device 140, and areconnected to processing circuitry 142 to allow processing circuitry 142to output information from wireless device 140. For example, outputinterfaces, devices, or circuits may include a speaker, a display,vibrating circuitry, a USB port, a headphone interface, or other outputelements. Using one or more input and output interfaces, devices, andcircuits, wireless device 140 may communicate with end users and/or thewireless network, and allow them to benefit from the functionalitydescribed herein.

As another example, wireless device or UE 140 may include power source149. Power source 149 may comprise power management circuitry. Powersource 149 may receive power from a power supply, which may either becomprised in, or be external to, power source 149. For example, wirelessdevice 140 may comprise a power supply in the form of a battery orbattery pack which is connected to, or integrated in, power source 149.Other types of power sources, such as photovoltaic devices, may also beused. As a further example, wireless device 140 may be connectable to anexternal power supply (such as an electricity outlet) via an inputcircuitry or interface such as an electrical cable, whereby the externalpower supply supplies power to power source 149. Power source 149 may beconnected to radio front-end circuitry 148, processing circuitry 142,and/or computer-readable storage medium 145 and be configured to supplywireless device 140, including processing circuitry 142, with power forperforming the functionality described herein.

Wireless device 140 may also include multiple sets of processingcircuitry 142, computer-readable storage medium 145, radio circuitry148, and/or antenna 147 for different wireless technologies integratedinto wireless device 140, such as, for example, GSM, WCDMA, LTE, NR,WiFi, or Bluetooth wireless technologies. These wireless technologiesmay be integrated into the same or different chipsets and othercomponents within wireless device 140.

Any appropriate steps, methods, or functions described herein may alsobe performed through one or more functional modules.

Referring to FIG. 14c , the wireless device 140 may comprise an antenna147, a processing module 14200, a transceiving module 14300 and astoring module 14500 that may perform steps or functions describedherein in relation with some embodiments.

Referring to FIG. 14d , the network node 1440 may comprise a processingmodule 14420, a transceiving module 14410 and a storing module 14430that may perform steps or functions described herein in relation withsome embodiments.

Each functional module may comprise software, computer programs,sub-routines, libraries, source code, or any other form of executableinstructions that are executed by, for example, a processor. In someembodiments, each functional module may be implemented in hardwareand/or in software. For example, one or more or all functional modulesmay be implemented by processors 142 and/or 1442, possibly incooperation with storage 145 and/or 1443. Processors 142 and/or 1442 andstorage 145 and/or 1443 may thus be arranged to allow processors 142and/or 1442 to fetch instructions from storage 145 and/or 1443 andexecute the fetched instructions to allow the respective functionalmodule to perform any steps or functions disclosed herein.

FIG. 15 is a schematic block diagram illustrating a virtualizationenvironment 1500 in which functions implemented by some embodiment(s)may be virtualized. As used herein, virtualization can be applied to anode (e.g., a virtualized base station or a virtualized radio accessnode), in the present case the location server, or to a device (e.g.user device or any type of wireless communication device) and relates toan implementation in which at least a portion of the functionality isimplemented as a virtual component(s) (e.g., viaapplication(s)/component(s)/function(s) or virtual machine(s) executingon a physical processing node(s) in a network(s)).

In some embodiments, some or all of the functions described herein maybe implemented as virtual components executed by one or more virtualmachines implemented in a virtual environment(s) hosted by the hardwarenode(s) 1530. Further, in embodiments in which the virtual node is not aradio access node or does not require radio connectivity (e.g., a corenetwork node or a location server), then the network node may beentirely virtualized.

The functions may be implemented by an application 1520 (which mayalternatively be called a software instance, a virtual appliance, anetwork function, a virtual node, or a virtual network function)operative to implement steps of some method(s) according to someembodiment(s). The application 1520 runs in a virtualization environment1500 which provides hardware 1530 comprising processing circuitry 1560and memory 1590. The memory contains instructions 1595 executable by theprocessing circuitry 1560 whereby the application 1520 is operative toexecute the method(s) or steps of the method(s) previously described inrelation with some embodiment(s). The virtualization environment 1500,comprises a general-purpose or special-purpose network hardwaredevice(s) 1530 comprising a set of one or more processor(s) orprocessing circuitry 1560, which may be commercial off-the-shelf (COTS)processors, dedicated Application Specific Integrated Circuits (ASICs),or any other type of processing circuitry including digital or analoghardware components or special purpose processors. The hardwaredevice(s) comprises a memory 1590-1 which may be a transitory memory forstoring instructions 1595 or software executed by the processingcircuitry 1560. The hardware device(s) comprises network interfacecontroller(s) 1570 (NICs), also known as network interface cards, whichinclude physical Network Interface 1580. The hardware device(s) alsoincludes non-transitory machine-readable storage media 1590-2 havingstored therein software 1595 and/or instruction executable by theprocessing circuitry 1560. Software 1595 may include any type ofsoftware including software for instantiating the virtualization layeror hypervisor, software to execute virtual machines 1540 as well assoftware allowing to execute functions described in relation with someembodiment(s) described previously.

Virtual machines 1540, implement virtual processing, virtual memory,virtual networking or interface and virtual storage, and may be run bythe virtualization layer or hypervisor 1550. Different embodiments ofthe instance or virtual appliance 1520 may be implemented on one or moreof the virtual machine(s) 1540, and the implementations may be made indifferent ways.

During operation, the processing circuitry 1560 executes software 1595to instantiate the hypervisor or virtualization layer, which maysometimes be referred to as a virtual machine monitor (VMM). Thehypervisor 1550 may present a virtual operating platform that appearslike networking hardware to virtual machine 1540. As shown in the FIG.15, hardware 1530 may be a standalone network node, with generic orspecific hardware. Hardware 1530 may comprise an antenna 15225 and mayimplement some functions via virtualization. Alternatively, hardware1530 may be part of a larger cluster of hardware (e.g. such as in a datacenter or customer premise equipment (CPE)) where many hardware nodeswork together and are managed via management and orchestration (MANO)15100, which, among others, oversees lifecycle management ofapplications 1520.

Virtualization of the hardware is in some contexts referred to asnetwork function virtualization (NFV). NFV may be used to consolidatemany network equipment types onto industry standard high-volume serverhardware, physical switches, and physical storage, which can be locatedin Data centers, and customer premise equipment. In an embodiment, thelocation server or functions thereof could be virtualized.

In the context of NFV, a virtual machine 1540 is a softwareimplementation of a physical machine that runs programs as if they wereexecuting on a physical, non-virtualized machine. Each of the virtualmachines 1540, and that part of the hardware 1530 that executes thatvirtual machine, be it hardware dedicated to that virtual machine and/ortime slices of hardware temporally shared by that virtual machine withothers of the virtual machine(s) 1540, forms a separate virtual networkelement(s) (VNE). Still in the context of NFV. Virtual Network Function(VNF) is responsible for handling specific network functions that run inone or more virtual machines on top of the hardware networkinginfrastructure and corresponds to application 1520 in FIG. 15.

In some embodiments, one or more radio units 15200 that each includesone or more transmitters 15220 and one or more receivers 15210 may becoupled to one or more antennas 15225. The radio units 15200 maycommunicate directly with hardware node(s) 1530 via an appropriatenetwork interface(s) and may be used in combination with the virtualcomponents to provide a virtual node with radio capabilities, such as aradio access node or a base station.

In some embodiments, some signaling can be effected with the use of acontrol system 15230 which may alternatively be used for communicationbetween the hardware node(s) 1530 and the radio unit(s) 15200.

Modifications and other embodiments will come to mind to one skilled inthe art having the benefit of the teachings presented in the foregoingdescription and the associated drawings. Therefore, it is to beunderstood that modifications and other embodiments, such as specificforms other than those of the embodiments described above, are intendedto be included within the scope of this disclosure. The describedembodiments are merely illustrative and should not be consideredrestrictive in any way. The scope sought is given by the appendedclaims, rather than the preceding description, and all variations andequivalents that fall within the range of the claims are intended to beembraced therein. Although specific terms may be employed herein, theyare used in a generic and descriptive sense only and not for purposes oflimitation.

1. A method, executed in a target device, for providing Observed TimeDifference of Arrival (OTDOA) Reference Signal Time Difference (RSTD)measurements to a location server, comprising the steps of: sending, tothe location server, an indication of a capability to support OTDOAlocation measurements using multipath RSTD; receiving a request forOTDOA location measurements using multipath RSTD, from the locationserver; receiving assistance data providing details of required OTDOAlocation measurements using multipath RSTD, from the location server;receiving a signal from an RSTD reference cell and from a neighbor cell;observing a time difference between the received signals therebyobtaining the required OTDOA location measurements using multipath RSTD;and sending the required OTDOA location measurements using multipathRSTD to the location server.
 2. The method of claim 1, wherein theneighbor cell for which the time difference is to be observed isindicated by the location server in the assistance data.
 3. The methodof claim 1, wherein the assistance data contains an indication thattriggers the target device to search for additional peaks in at leastone received signal.
 4. The method of claim 3, wherein the locationserver triggers the execution of the method based on historicalinformation indicating that the target device has previously reportedmeasurements using multipath RSTD.
 5. The method of claim 3, wherein thelocation server triggers the execution of the method based on historicalinformation indicating that the target device has previously beenpositioned with poor accuracy.
 6. The method of claim 3, wherein thetarget device has previously been positioned based on at least twopositioning methods such as Global Navigation Satellite System (GNSS)and OTDOA RSTD.
 7. The method of claim 1, wherein the step of observingfurther comprises using a peak-probability threshold of a given value toestimate the OTDOA location measurements using multipath RSTD, where ahigher threshold provides better robustness to noise.
 8. The method ofclaim 7, wherein the target device is operative to exclude non-line ofsight (NLOS) OTDOA location measurements, thereby allowing to set alower peak-probability threshold.
 9. The method of claim 7, wherein thepeak-probability is configured by the location server and is provided tothe target device.
 10. The method of claim 7, wherein thepeak-probability threshold is based on cell deployment data and anetwork positioning algorithm, wherein the OTDOA location measurementsusing multipath RSTD are based on identified valid peaks of signals fromthe reference and neighbor cells, wherein a valid peak is a peak abovethe peak-probability threshold, and wherein the OTDOA locationmeasurements using multipath RSTD are determined as the firsts of thevalid peaks from the reference and neighbor cells.
 11. A method,executed in a location server, for receiving Observed Time Difference ofArrival (OTDOA) Reference Signal Time Difference (RSTD) measurementsfrom a target device, comprising the steps of: receiving an indicationof a capability to support OTDOA location measurements using multipathRSTD, from the target device; sending a request for OTDOA locationmeasurements using multipath RSTD, to the target device; sendingassistance data providing details of required OTDOA locationmeasurements using multipath RSTD, to the target device; and receivingthe required OTDOA location measurements using multipath RSTD, from thetarget device.
 12. The method of claim 11, wherein the location serverindicates in the assistance data a neighbor cell for which a timedifference is to be observed by the target device.
 13. The method ofclaim 11, wherein the location server triggers the target device tosearch for additional peaks in at least one received signal through anindication in the assistance data.
 14. The method of claim 13, whereinthe location server triggers the execution of the method based onhistorical information indicating that the target device has previouslyreported measurements using multipath RSTD.
 15. The method of claim 13,wherein the location server triggers the execution of the method basedon historical information indicating that the target device haspreviously been positioned with poor accuracy.
 16. The method of claim13, wherein the target device has previously been positioned based on atleast two positioning methods such as Global Navigation Satellite System(GNSS) and OTDOA RSTD.
 17. The method of claim 11, wherein the locationserver provides a peak-probability threshold of a given value to thetarget device for estimation of the OTDOA location measurements usingmultipath RSTD, where a higher threshold provides better robustness tonoise.
 18. The method of claim 17, wherein the peak-probabilitythreshold is based on cell deployment data and a network positioningalgorithm, wherein the OTDOA location measurements using multipath RSTDare based on identified valid peaks of signals from the reference andneighbor cells, wherein a valid peak is a peak above thepeak-probability threshold, and wherein the OTDOA location measurementsusing multipath RSTD are determined as the firsts of the valid peaks.19. A wireless device operative to provide Observed Time Difference ofArrival (OTDOA) Reference Signal Time Difference (RSTD) measurements toa location server, the wireless device comprising processing circuitryand a memory, said memory containing instructions executable by saidprocessing circuitry whereby said wireless device is operative to: send,to the location server, an indication of a capability to support OTDOAlocation measurements using multipath RSTD; receive a request for OTDOAlocation measurements using multipath RSTD, from the location server;receive assistance data providing details of required OTDOA locationmeasurements using multipath RSTD, from the location server; receive asignal from an RSTD reference cell and from a neighbor cell; observe atime difference between the received signals thereby obtaining therequired OTDOA location measurements using multipath RSTD; and send therequired OTDOA location measurements using multipath RSTD to thelocation server.
 20. The wireless device of claim 19, wherein theneighbor cell for which the time difference is to be observed isindicated by the location server in the assistance data.
 21. Thewireless device of claim 19, wherein the assistance data contains anindication that triggers the wireless device to search for additionalpeaks in at least one received signal.
 22. The wireless device of claim21, wherein the execution of the method is triggered by the locationserver based on historical information indicating that the wirelessdevice has previously reported measurements using multipath RSTD. 23.The wireless device of claim 21, wherein the execution of the method istriggered by the location server based on historical informationindicating that the wireless device has previously been positioned withpoor accuracy.
 24. The wireless device of claim 21, wherein the wirelessdevice has previously been positioned based on at least two positioningmethods such as Global Navigation Satellite System (GNSS) and OTDOARSTD.
 25. The wireless device of claim 19, further operative to observethe time difference using a peak-probability threshold of a given valueto estimate the OTDOA location measurements using multipath RSTD, wherea higher threshold provides better robustness to noise.
 26. The wirelessdevice of claim 25, further operative to exclude non-line of sight(NLOS) OTDOA location measurements, thereby allowing to set a lowerpeak-probability threshold.
 27. The wireless device of claim 25, whereinthe peak-probability is configured by the location server and isprovided to the wireless device.
 28. The wireless device of claim 25,wherein the peak-probability threshold is based on cell deployment dataand a network positioning algorithm, wherein the OTDOA locationmeasurements using multipath RSTD are based on identified valid peaks ofsignals from the reference and neighbor cells, wherein a valid peak is apeak above the peak-probability threshold, and wherein the OTDOAlocation measurements using multipath RSTD are determined as the firstsof the valid peaks from the reference and neighbor cells.
 29. A locationserver operative to receive Observed Time Difference of Arrival (OTDOA)Reference Signal Time Difference (RSTD) measurements from a wirelessdevice, the location server comprising processing circuitry and amemory, said memory containing instructions executable by saidprocessing circuitry whereby said location server is operative to:receive an indication of a capability to support OTDOA locationmeasurements using multipath RSTD, from a wireless device; send arequest for OTDOA location measurements using multipath RSTD, to thewireless device; send assistance data providing details of requiredOTDOA location measurements using multipath RSTD, to the wirelessdevice; and receive the required OTDOA location measurements usingmultipath RSTD, from the wireless device.
 30. The location server ofclaim 29, wherein the location server indicates in the assistance data aneighbor cell for which a time difference is to be observed by thetarget device.
 31. The location server of claim 29, wherein the locationserver triggers the target device to search for additional peaks in atleast one received signal through an indication in the assistance data.32. The location server of claim 31, wherein the location servertriggers the execution of the method based on historical informationindicating that the target device has previously reported measurementsusing multipath RSTD.
 33. The location server of claim 31, wherein thelocation server triggers the execution of the method based on historicalinformation indicating that the target device has previously beenpositioned with poor accuracy.
 34. The location server of claim 31,wherein the target device has previously been positioned based on atleast two positioning methods such as Global Navigation Satellite System(GNSS) and OTDOA RSTD.
 35. The location server of claim 29, wherein thelocation server provides a peak-probability threshold of a given valueto the target device for estimation of the OTDOA location measurementsusing multipath RSTD, where a higher threshold provides betterrobustness to noise.
 36. The location server of claim 35, wherein thepeak-probability threshold is based on cell deployment data and anetwork positioning algorithm, wherein the OTDOA location measurementsusing multipath RSTD are based on identified valid peaks of signals fromthe reference and neighbor cells, wherein a valid peak is a peak abovethe peak-probability threshold, and wherein the OTDOA locationmeasurements using multipath RSTD are determined as the firsts of thevalid peaks.
 37. (canceled)